A limited slip differential in a vehicle typically employs a wet multi-plate clutch, i.e., clutch plates are immersed in a lubricant. The limited slip differential typically has bevel gear or spur gear planetary systems which distribute the drive torque evenly to the two driving wheels irrespective of their rotational speed. This makes it possible for the driven wheels to roll during cornering without slip between the wheel and road surface in spite of their different rotational speed. In order for the slip to be controlled lubricants containing compounds capable of improving friction performance, dispersants and sulphur- and/or phosphorus-containing extreme pressure agents may be used. Examples of lubricants of this type are disclosed in U.S. Pat. Nos. 4,308,154; 5,547,586; 4,180,466; 3,825,495; and European Patent Application 0 399 764 A1.
Lubricants containing compounds suitable for (i) deposit control (U.S. Pat. No. 3,284,409), and (ii) wear performance are described in International Application WO 96/037585, US Patent Application 2002/0119895, and U.S. Pat. No. 5,487,838.